It is known to provide a safety cabinet of the type used to store dangerous chemicals or tools with a folding door having a plurality of panels that are coplanar and cover an open side of the cabinet when closed and that fold up to give access to the open side when open. In a typical such door there are four panels including two outer panels and two inner panels between the outer panels. Each outer panel is coupled via a link mechanism to the respective inner panel, and the two link mechanisms are in turn connected together for joint and synchronous movement between the inner and outer positions.
German patent document 20 2004 004 855 describes such a cabinet. Here each door is equipped with a synchronizing lever and also with a link lever. The synchronizing levers are hinged to one another via a connecting element that moves in a guide. The guide runs perpendicular to a plane the doors lie in when closed and that is perpendicular to a center plane of the cabinet symmetrically flanked by the vertical pivot axes of the door panels.
In addition there is a spring that biases the doors shut and that extends along the guide or is accommodated therein. True synchronous movement of the doors is supposed to be enabled in this manner without one of the doors having to follow the other or vice versa. In addition, it serves to hold the doors in the open position.
This system has proven itself in terms of one-handed operation of the two folding doors due to the connecting element. However, the mechanical complexity is relatively high and the actuating spring is actuated every time the door is opened or closed. This spring is a scroll spring that is anchored at one end in the cabinet. The anchor is connected to the cabinet via a temperature-dependent fusible connecting element so the door closes automatically if there is a fire. As a result it is not always possible to preclude functional limitations because the known scroll spring is operated during each closing process and it is therefore subject to metal fatigue. This is particularly true of the temperature-dependent fusible connecting element so that in general functional reliability cannot always be assured, especially if there is a fire.
The same is also true for the system in accordance with German patent document 200 19 307. In the case of this safety cabinet, the automatically closing folding door has two hinged folding panels. One folding panel is connected to a lever that can be directly or indirectly rotated by a door closer. One end of the lever is connected to an axis shaft that is pivoted on the door closer or a wall of the safety cabinet. The other end of the lever is connected to the second folding door that is hinged, directly or indirectly, to the first folding door, which is itself pivoted on the cabinet.